const autoprefixer = require("autoprefixer")
const path = require("path")
const fs = require("fs")
const webpack = require("webpack")
const HtmlWebpackPlugin = require("html-webpack-plugin")
const ExtractTextPlugin = require("extract-text-webpack-plugin")
const ManifestPlugin = require("webpack-manifest-plugin")
const InterpolateHtmlPlugin = require("react-dev-utils/InterpolateHtmlPlugin")
const SWPrecacheWebpackPlugin = require("sw-precache-webpack-plugin")
const eslintFormatter = require("react-dev-utils/eslintFormatter")
const ModuleScopePlugin = require("react-dev-utils/ModuleScopePlugin")
const paths = require("./paths")
const getClientEnvironment = require("./env")
const tmpVersion = "local_" + (Math.floor(Math.random() * 1e6)).toString()
const VERSION = process.env.TAG_NAME || tmpVersion		// webpack 不让传自定义参数

function resolve(dir) {
	return path.join(__dirname, "..", dir)
}

// Webpack uses `publicPath` to determine where the app is being served from.
// It requires a trailing slash, or the file assets will get an incorrect path.
const publicPath = "./" //paths.servedPath
// Some apps do not use client-side routing with pushState.
// For these, "homepage" can be set to "." to enable relative asset paths.
const shouldUseRelativeAssetPaths = publicPath === "./"
// `publicUrl` is just like `publicPath`, but we will provide it to our app
// as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
// Omit trailing slash as %PUBLIC_URL%/xyz looks better than %PUBLIC_URL%xyz.
const publicUrl = publicPath.slice(0, -1)
// Get environment variables to inject into our app.
const env = getClientEnvironment(publicUrl)

// Assert this just to be safe.
// Development builds of React are slow and not intended for production.
if (env.stringified["process.env"].NODE_ENV !== '"production"') {
	throw new Error("Production builds must have NODE_ENV=production.")
}

// Note: defined here because it will be used more than once.
const cssFilename = "static/css/[name].[contenthash:8].css"

// ExtractTextPlugin expects the build output to be flat.
// (See https://github.com/webpack-contrib/extract-text-webpack-plugin/issues/27)
// However, our output is structured with css, js and media folders.
// To have this structure working with relative paths, we have to use custom options.
const extractTextPluginOptions = shouldUseRelativeAssetPaths
	? // Making sure that the publicPath goes back to to build folder.
		{ publicPath: Array(cssFilename.split("/").length).join("../") }
	: {}

// This is the production configuration.
// It compiles slowly and is focused on producing a fast and minimal bundle.
// The development configuration is different and lives in a separate file.
module.exports = {
	// Don't attempt to continue if there are any errors.
	bail: true,
	// We generate sourcemaps in production. This is slow but gives good results.
	// You can exclude the *.map files from the build during deployment.
	devtool: "source-map",
	// In production, we only want to load the polyfills and the app code.
	entry: {
		"WebIMConfig": paths.appConfigJs,
		"index": [require.resolve("./polyfills"), paths.appIndexJs]
	},
	externals: {
		WebIMConfig: 'WebIMConfig'
	},
	watch: true,
	output: {
		// The build folder.
		path: paths.appBuild,
		// Generated JS file names (with nested folders).
		// There will be one main bundle, and one file per asynchronous chunk.
		// We don't currently advertise code splitting but Webpack supports it.
		filename: "static/js/[name].[chunkhash:8].js",
		chunkFilename: "static/js/[name].[chunkhash:8].chunk.js",
        library: 'WebIMConfig',
        libraryTarget: 'umd',
		// We inferred the "public path" (such as / or /my-project) from homepage.
		publicPath: publicPath,
		// Point sourcemap entries to original disk location (format as URL on Windows)
		devtoolModuleFilenameTemplate: info =>
			path.relative(paths.appSrc, info.absoluteResourcePath).replace(/\\/g, "/")
	},
	resolve: {
		// This allows you to set a fallback for where Webpack should look for modules.
		// We placed these paths second because we want `node_modules` to "win"
		// if there are any conflicts. This matches Node resolution mechanism.
		// https://github.com/facebookincubator/create-react-app/issues/253
		modules: ["node_modules", paths.appNodeModules].concat(
			// It is guaranteed to exist because we tweak it in `env.js`
			process.env.NODE_PATH.split(path.delimiter).filter(Boolean)
		),
		// These are the reasonable defaults supported by the Node ecosystem.
		// We also include JSX as a common component filename extension to support
		// some tools, although we do not recommend using it, see:
		// https://github.com/facebookincubator/create-react-app/issues/290
		// `web` extension prefixes have been added for better support
		// for React Native Web.
		extensions: [".web.js", ".js", ".json", ".web.jsx", ".jsx"],
		alias: {
			// Support React Native Web
			// https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
			"react-native": "react-native-web",
			"@": resolve("src")
		},
		plugins: [
			// Prevents users from importing files from outside of src/ (or node_modules/).
			// This often causes confusion because we only process files within src/ with babel.
			// To fix this, we prevent you from importing files out of src/ -- if you'd like to,
			// please link the files into your node_modules/ and let module-resolution kick in.
			// Make sure your source files are compiled, as they will not be processed in any way.
			new ModuleScopePlugin(paths.appSrc),
			new webpack.optimize.CommonsChunkPlugin({
				name: "WebIMConfig",
				chunks: ["WebIMConfig"]
			})
		]
	},
	module: {
		strictExportPresence: true,
		rules: [
			// TODO: Disable require.ensure as it's not a standard language feature.
			// We are waiting for https://github.com/facebookincubator/create-react-app/issues/2176.
			// { parser: { requireEnsure: false } },

			// First, run the linter.
			// It's important to do this before Babel processes the JS.
			// {
			// 	test: /\.(js|jsx)$/,
			// 	enforce: "pre",
			// 	use: [
			// 		{
			// 			options: {
			// 				formatter: eslintFormatter
			// 			},
			// 			loader: require.resolve("eslint-loader")
			// 		}
			// 	],
			// 	include: paths.appSrc
			// },
			// ** ADDING/UPDATING LOADERS **
			// The "file" loader handles all assets unless explicitly excluded.
			// The `exclude` list *must* be updated with every change to loader extensions.
			// When adding a new loader, you must add its `test`
			// as a new entry in the `exclude` list in the "file" loader.

			// "file" loader makes sure those assets end up in the `build` folder.
			// When you `import` an asset, you get its filename.
			{
				exclude: [
					/\.html$/,
					/\.(js|jsx)$/,
					/\.css$/,
					/\.less$/,
					/\.json$/,
					/\.bmp$/,
					/\.gif$/,
					/\.jpe?g$/,
					/\.png$/
				],
				loader: require.resolve("file-loader"),
				options: {
					name: "static/media/[name].[hash:8].[ext]"
				}
			},
			// "url" loader works just like "file" loader but it also embeds
			// assets smaller than specified size as data URLs to avoid requests.
			{
				test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
				loader: require.resolve("url-loader"),
				options: {
					limit: 10000,
					name: "static/media/[name].[hash:8].[ext]"
				}
			},
			// Process JS with Babel.
			{
				test: /\.(js|jsx)$/,
				exclude: paths.appConfigJs,
				include: paths.appSrc,
				loader: require.resolve("babel-loader"),
				options: {
					compact: true
				}
			},
			// The notation here is somewhat confusing.
			// "postcss" loader applies autoprefixer to our CSS.
			// "css" loader resolves paths in CSS and adds assets as dependencies.
			// "style" loader normally turns CSS into JS modules injecting <style>,
			// but unlike in development configuration, we do something different.
			// `ExtractTextPlugin` first applies the "postcss" and "css" loaders
			// (second argument), then grabs the result CSS and puts it into a
			// separate file in our build process. This way we actually ship
			// a single CSS file in production instead of JS code injecting <style>
			// tags. If you use code splitting, however, any async bundles will still
			// use the "style" loader inside the async code so CSS from them won't be
			// in the main CSS file.
			{
				test: /\.css$/,
				loader: ExtractTextPlugin.extract(
					Object.assign(
						{
							fallback: require.resolve("style-loader"),
							use: [
								{
									loader: require.resolve("css-loader"),
									options: {
										importLoaders: 1,
										minimize: true,
										sourceMap: true
									}
								},
								{
									loader: require.resolve("postcss-loader"),
									options: {
										// Necessary for external CSS imports to work
										// https://github.com/facebookincubator/create-react-app/issues/2677
										ident: "postcss",
										plugins: () => [
											require("postcss-flexbugs-fixes"),
											autoprefixer({
												browsers: [
													">1%",
													"last 4 versions",
													"Firefox ESR",
													"not ie < 9" // React doesn't support IE8 anyway
												],
												flexbox: "no-2009"
											})
										]
									}
								}
							]
						},
						extractTextPluginOptions
					)
				)
				// Note: this won't work without `new ExtractTextPlugin()` in `plugins`.
			},
			// ** STOP ** Are you adding a new loader?
			// Remember to add the new extension(s) to the "file" loader exclusion list.
			{
				test: /\.less$/,
				use: [
					require.resolve("style-loader"),
					{
						loader: require.resolve("css-loader")
						// options: {
						// 	importLoaders: 1
						// }
					},
					{
						loader: require.resolve("postcss-loader"),
						options: {
							// Necessary for external CSS imports to work
							// https://github.com/facebookincubator/create-react-app/issues/2677
							ident: "postcss",
							plugins: () => [
								require("postcss-flexbugs-fixes"),
								autoprefixer({
									browsers: [
										">1%",
										"last 4 versions",
										"Firefox ESR",
										"not ie < 9" // React doesn't support IE8 anyway
									],
									flexbox: "no-2009"
								})
							]
						}
					},
					{
						loader: require.resolve("less-loader"),
						options: {
							// modifyVars: getThemeConfig()
						}
					}
				]
			}
		]
	},
	plugins: [
		// Makes some environment variables available in index.html.
		// The public URL is available as %PUBLIC_URL% in index.html, e.g.:
		// <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
		// In production, it will be an empty string unless you specify "homepage"
		// in `package.json`, in which case it will be the pathname of that URL.
		new InterpolateHtmlPlugin(env.raw),
		// Generates an `index.html` file with the <script> injected.
		new HtmlWebpackPlugin({
			inject: true,
			template: paths.appHtml,
			chunks: ['WebIMConfig', 'index'],
			chunksSortMode: 'manual',
			version: VERSION,
			minify: {
				removeComments: true,
				collapseWhitespace: true,
				removeRedundantAttributes: true,
				useShortDoctype: true,
				removeEmptyAttributes: true,
				removeStyleLinkTypeAttributes: true,
				keepClosingSlash: true,
				minifyJS: true,
				minifyCSS: true,
				minifyURLs: true
			}
		}),
		// Makes some environment variables available to the JS code, for example:
		// if (process.env.NODE_ENV === 'production') { ... }. See `./env.js`.
		// It is absolutely essential that NODE_ENV was set to production here.
		// Otherwise React will be compiled in the very slow development mode.
		new webpack.DefinePlugin(env.stringified),
		// Minify the code.
		new webpack.optimize.UglifyJsPlugin({
            exclude: /WebIMConfig/,
			compress: {
				warnings: false,
				// Disabled because of an issue with Uglify breaking seemingly valid code:
				// https://github.com/facebookincubator/create-react-app/issues/2376
				// Pending further investigation:
				// https://github.com/mishoo/UglifyJS2/issues/2011
				comparisons: false
			},
			output: {
				comments: false,
				// Turned on because emoji and regex is not minified properly using default
				// https://github.com/facebookincubator/create-react-app/issues/2488
				ascii_only: true
			},
			sourceMap: true
		}),
		// Note: this won't work without ExtractTextPlugin.extract(..) in `loaders`.
		new ExtractTextPlugin({
			filename: cssFilename
		}),
		// Generate a manifest file which contains a mapping of all asset filenames
		// to their corresponding output file so that tools can pick it up without
		// having to parse `index.html`.
		new ManifestPlugin({
			fileName: "asset-manifest.json"
		}),
		// Generate a service worker script that will precache, and keep up to date,
		// the HTML & assets that are part of the Webpack build.
		new SWPrecacheWebpackPlugin({
			// By default, a cache-busting query parameter is appended to requests
			// used to populate the caches, to ensure the responses are fresh.
			// If a URL is already hashed by Webpack, then there is no concern
			// about it being stale, and the cache-busting can be skipped.
			dontCacheBustUrlsMatching: /\.\w{8}\./,
			filename: "service-worker.js",
			logger(message) {
				if (message.indexOf("Total precache size is") === 0) {
					// This message occurs for every build and is a bit too noisy.
					return
				}
				if (message.indexOf("Skipping static resource") === 0) {
					// This message obscures real errors so we ignore it.
					// https://github.com/facebookincubator/create-react-app/issues/2612
					return
				}
				console.log(message)
			},
			minify: true,
			// For unknown URLs, fallback to the index page
			navigateFallback: publicUrl + "/index.html",
			// Ignores URLs starting from /__ (useful for Firebase):
			// https://github.com/facebookincubator/create-react-app/issues/2237#issuecomment-302693219
			navigateFallbackWhitelist: [/^(?!\/__).*/],
			// Don't precache sourcemaps (they're large) and build asset manifest:
			staticFileGlobsIgnorePatterns: [/\.map$/, /asset-manifest\.json$/]
		}),
		// Moment.js is an extremely popular library that bundles large locale files
		// by default due to how Webpack interprets its code. This is a practical
		// solution that requires the user to opt into importing specific locales.
		// https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
		// You can remove this if you don't use Moment.js:
		new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/)
	],
	// Some libraries import Node modules but don't use them in the browser.
	// Tell Webpack to provide empty mocks for them so importing them works.
	node: {
		dgram: "empty",
		fs: "empty",
		net: "empty",
		tls: "empty"
	}
}

function getThemeConfig() {
	const pkgPath = path.resolve(__dirname, "../package.json")
	const pkg = fs.existsSync(pkgPath) ? require(pkgPath) : {}

	let theme = {}
	if (pkg.theme && typeof pkg.theme === "string") {
		let cfgPath = pkg.theme
		// relative path
		if (cfgPath.charAt(0) === ".") {
			cfgPath = path.resolve(__dirname, "../" + cfgPath)
		}
		const getThemeConfigByJS = require(cfgPath)
		theme = getThemeConfigByJS
	} else if (pkg.theme && typeof pkg.theme === "object") {
		theme = pkg.theme
	}

	return theme
}
